Certain products, including drinks, contain, in a liquid component thereof, solid constituents. Examples of such solid constituents include product pieces, cells, and fibers.
When filling these products, it is important for the solid constituents to reach the particular container as intact as possible, i.e. as undamaged as possible. This will meet consumers' quality expectations and help to avoid complaints.
Damage to the solid constituents arises from thermal or mechanical causes. Thermal damages can occur as a result of overly long heating of the filling material. Mechanical damage can arise from shearing forces from product-damaging fittings in the flow paths for filling material in a filling system.
Examples of product-damaging fittings include adjustment and control valves, overflow valves, and, to a lesser degree, pumps used to transport the filling material. When operated at high speed, displacement pumps can cause product damage. However, displacement pumps are less likely to cause damage than dynamic pumps. For this reason, it is common in the beverage industry to transport products containing solid constituents using displacement pumps. Suitable pumps that have been used include reciprocating pumps, rotary piston pumps, and diaphragm pumps.
For hot filling or hot aseptic filling of products, including those with solid constituents, it is know to use filling systems in which a processing unit supplies the hot filling material or product and feeds it to the filling tank of a container-filling machine at a volume flow rate that is greater than the current filling or pour rate of the container-filling machine. Part of the supplied filling material supplied is fed through the container-filling machine and its filling elements and returned to the processing unit by a by-pass pipe. This part is referred to as “by-pass volume flow.”
A bypass pump adjusts the by-pass volume flow so as to keep the container-filling machine at the required temperature solely by the by-pass volume flow of the filling material. The control or adjustment of the by-pass pump or its delivery rate occurs depending on a temperature sensor provided on the container filling machine. However, higher delivery rates or high pump speeds are difficult to avoid.
Depending on the operating status of the container-filling machine used for hot filling, different by-pass volume flows are required. For example, the required volume flow for heating-up of the container filling machine during a production preparation phase may be different from that required during the operation of the container-filling machine, or that required during a machine stoppage due to a production interruption. These different by-pass quantities or by-pass volume flows are often expressed as a volume percentage of a nominal pour rate of the container filling machine. In a typical installation, the by-pass volume flow during the starting-up and heating-up of the filling machine is around 0% of the nominal pour rate, during the normal problem-free operation, it is around 5 to 10% of the nominal pour rate, and during a product interruption, it is between 5% and 10% of the nominal pour rate. This variability in bypass flow rate arises from control and/or adjustment of the by-pass pump.
Moreover, in filling systems, it is also known that the volume flow of the filling material supplied by the processing unit can largely be regarded as constant due to the thermal inertia of the processing unit. Thus, depending on the current operating status of the filling machine, a certain quantity of the filling material supplied by the processing unit is to be diverted, for example in the event of an emergency halt of the filling machine, 100% of the volume flow provided by the processing unit.
Thus, on the one hand, account is taken of the fact that the heat exchangers usually used to heat the filling material in the processing units only work effectively if a minimum volume flow of the filling material flows through them, and that the processing unit is generally not able to adapt the filling material quantity supplied by it or the volume flow supplied by it without delay to changes in the pour rate of the container-filling machine. In known filling systems, the overflow pipe made formed by the overflow valve is thus used for this adaptation on the one hand. To hold the level of the filling material constant in a filling tank of the container-filling machine, in known filling systems, a control valve is needed. The control valve is provided in the primary pipe connecting the processing unit to the filling tank of the container-filling machine.
A disadvantage in known filling systems arises from the high stress on the solid constituents contained in the filling material due to product-damaging fittings. This arises as a result of the adjustment or control valve needed in the primary pipe, the overflow valve provided in the overflow pipe, and the by-pass pump driven by the relatively high delivery rate. Another known disadvantage of such filling systems is the high consumption of energy consumption that arises when a substantial volume flows through a substantial pressure difference.